An astronaut whose weight on the Earth is 600 N experiences weightless- ness on International Space Station orbiting around the Earth. It means that

CONCEPT:

Weightlessness in Space

• Weightlessness occurs when there is no net force acting on a body, making it appear as though it has no weight.
• In the context of an astronaut on the International Space Station (ISS), this sensation is due to the fact that both the astronaut and the ISS are in free-fall around the Earth.

EXPLANATION:

• An astronaut experiences weightlessness because:
  • The normal reaction of the space-station floor on the astronaut is zero.
  • The astronaut and the space station are both accelerating towards the Earth at the same rate due to gravity, creating a continuous free-fall scenario.
• However, it does not mean that:
  • The gravitational pull of Earth on the astronaut is zero. The gravitational force is still acting on the astronaut, which is why they are in orbit.
  • The acceleration of the astronaut is zero. They are accelerating towards the Earth due to gravity, but this acceleration is what creates the orbit.
  • The space station applies a centrifugal force on the astronaut. The sensation of weightlessness is due to the free-fall, not a centrifugal force.

Therefore, the correct statement is that the normal reaction of the space-station floor on the astronaut is zero.